Re: [Qemu-devel] vhost-user: migration?

[Zhang Haoyu]

Hi,
what's the status of migration support for vhost-user?

Thanks,
Zhang Haoyu
                                       
On 2014-06-18 22:07:49, Michael S. Tsirkin wrote:
> On Wed, Jun 18, 2014 at 04:37:57PM +0300, Nikolay Nikolaev wrote:
> > 
> > 
> > 
> > On Wed, Jun 18, 2014 at 3:35 PM, Michael S. Tsirkin <address@hidden> wrote:
> > 
> >     On Wed, Jun 18, 2014 at 02:41:15PM +0300, Nikolay Nikolaev wrote:
> >     >
> >     >
> >     >
> >     > On Wed, Jun 18, 2014 at 2:29 PM, Michael S. Tsirkin <address@hidden>
> >     wrote:
> >     >
> >     >     On Wed, Jun 18, 2014 at 02:24:32PM +0300, Nikolay Nikolaev wrote:
> >     >     > Hello,
> >     >     >
> >     >     > On Wed, Jun 18, 2014 at 12:33 PM, Michael S. Tsirkin <
> >     address@hidden>
> >     >     wrote:
> >     >     >
> >     >     >     Just a query whether migration works for you
> >     >     >     guys with vhost-user and snabbswitch.
> >     >     >
> >     >     >
> >     >     > I am not aware of anyone ever did such tests.
> >     >     >
> >     >     >
> >     >     >     vhost user code seems to have enough hooks in
> >     >     >     place to make it work, but was it tested
> >     >     >     in practice?
> >     >     >
> >     >     >
> >     >     >
> >     >     > Can you give some pointers of a simple/quick test scenario. 
> > Maybe
> >     we'll
> >     >     be able
> >     >     > to set it up.
> >     >
> >     >
> >     >     Basically migrate while doing networking :)
> >     >
> >     >     Does your vhost server have code to set bits in the memory log
> >     >     when logging is enabled?
> >     >
> >     >
> >     > No - we didn't implement this feature.
> > 
> >     Interesting. In that case vhost user should for now
> >     block migration.
> > 
> > Any place in the source where we can see example of similar behaviour?
> >  
> > 
> >     You must also check log feature and return failure.
> > 
> > Should this happen on the QEMU side? Is this the log feature of the device?
> > 
> > regards,
> > Nikolay Nikolaev
> >  
> 
> Well, QEMU is buggy in that it tries to set log
> flag without checking.
> I will fix that.
> 
> 
> However
> 1.  Your server must not publish the VHOST_F_LOG_ALL feature.
> 
> On vhost side it should validate features set
> match the supported mask.
> Also for flags in the virtqueue address structure.
> Please validate as much as possible, e.g.
> validate all unused fields are zero.
> If things work by mistake now you will have to maintain
> them indefinitely.
> 
> 
> 
> > 
> > 
> >     >
> >     >     The log address is supplied to VHOST_SET_LOG_BASE and 
> > log_guest_addr.
> >     >
> >     >
> >     >     >
> >     >     >
> >     >     >     --
> >     >     >     MST
> >     >     >
> >     >     >
> >     >     > regards,
> >     >     > Nikolay Nikolaev
> >     >
> >     >
> >     > regards,
> >     > Nikolay Nikolaev